Container opening devices



Sept. 20, 1966 E. c. FRAZE CONTAINER OPENING DEVICES 2 Sheets-Sheet 1Filed March 2, 1964 //VVJ"/VTOL irma/ 6'. Fr

% 7 ZZZ? Sept. 20, 1966 E. c. FRAZE- GONTAINER OPENING DEVICES 2Sheets-Sheet 2 Filed March 2, 1964 United States Patent 3,273,744CUNTAINER OPENING DEVICES Ermal C. Fraze, 355 W. Stroop Road, Dayton,()luo Filed Mar. 2, 1964, Ser. No. 348,618 8 Claims. (Cl. 22054) Thisapplication is a coutinuation-in-part of my copending application SerialNo. 280,545 [filed May 15, 1963 which in turn is a continuation-in-partof my applicatlon Serial 'No. 193,060 filed May 2, 1962, which is turnis a continuation-impart of my application Serial No. 130,884 filedAugust 11, 1961.

This invention relates to a container of the type which has a metal wallwith a score line forming a tear strip thereon and has a tab connectedto the tear strip to function as a manually operable second-class leverto initiate severance of the tear strip.

The present invention is directed towards certain needs for improvementwhich have become apparent with the development of a mass market forcontainers of this type.

One need is to increase the reliability and efiiciency of the leveraction for severance of the tear strip. The primary problem with respectto reliability is to keep the tab from tearing loose from the tear stripwhen the lever action is initiated. 'In the type of construction towhich the invention pertains the tear strip is connected to the tab by ahollow rivet that is formed in the metal of the tear strip and extendsthrough an aperture of the tab in overlapping engagement with the tab.One difiiculty is that the lever action of the tab initially tilts thehollow rivet and the high stress that is created tends to cause themetal of the tab to pull free from the hollow rivet on the side of thehollow rivet that is initially lifted.

Another difliculty is that in the usual construction, exceedingly highstress is necessary to initiate severance of the tear strip because thestress is distributed along a substantial portion of the scored lineinstead of being concentrated on at a point on the scored line. When thestress is distributed over a substantial portion of the scored line,increased force is necessary to initiate severance of the tear strip andthe increased force increases the tendency for the metal of the tearstrip to pull away from the rivet.

One embodiment of the invention meets both of these difiiculties by anumber of provisions, namely: first, tapering the leading end of thetear strip; second, by providing a hollow rivet which is elongated inplan; third, favoring initiation of the severance in a particular regionby placing the hollow rivet as close as possible to the tapered end ofthe tear strip so that two points of the score line that form thetapered end of the tear strip are located immediately adjacent oppositesides of the rivet respectively to favor initiation of the severance ofthe tear strip at the particular region of the two points; and, fourth,carrying out the operation of heading the elongated rivet in such mannerthat the metal that forms the head is displaced towards the tapered endof the tear strip to counter the tendency of the metal of the tear stripto pull away from the rivet.

In another embodiment of the invention, the same purpose is served byusing a round rivet and favoring initiation of the severance at aparticular region by making the score line reentrant relative to therivet. Thus the scored line is offset towards the rivet to a point closeto the rivet to cause initiation of the severance of the tear strip tooccur at the reentrant point.

The features and advantages of the invention may be understood from thefollowing detailed description and the accompanying drawings.

In the drawings, which are to be regarded as merely illustrative:

FIG. 1 is a fragmentary plan view of a can top embody-ing one practiceof the invention;

FIG. 2 is a fragmentary section along the angular line Q-2 showing oneof the two points at which the score line is immediately adjacent thehollow rivet;

FIG. 3 is a section of the can top taken along the diameter 3-4; of FIG.1;

FIG. 4 is a section along the line 4-4 of FIG. 6 showing how a pair ofdies cooperate to head the hollow rivet;

FIG. 5 is a transverse section of the rivet in the two dies taken alongthe line 55 of FIG. 4;

FIG. 6 is a section along the line 6-6 of FIG. 4 showing how the metalthat forms the head of the rivet is displaced towards the two oppositeends of the rivet;

FIG. 7 is a plan view of a can top illustrating a second practice of theinvention;

FIG. 8 is an enlarged fragment of FIG. 7 with a portion of the tabremoved to reveal the reentrant scored line under the tab;

FIG. 9 is a fragmentary section similar to FIG. 8 indicating theinitiation of the severance of the tear strip;

FIG. 10 is a similar view showing the severance operation at a moreadvanced stage;

FIG. 11 is a fragmentary section along the line 1'111 of FIG. 10; and

FIG. 12 is a sectional view similar to FIG. 11 showing a more advancedstage in the severance of the tear strip by the tab.

FIGS. 1, 2 and 3 illustrating one practice of the invention show themetal top 20 of a can that is intended to contain a beverage underpressure, the can top being made of a suitable material such as aluminumor steel. In preparation for joining the can top to a cylindrical canbody the can top 20 is offset in a conventional manner to form acircumferential groove 22 and a peripheral flange 24. The can top isscored along a continuous line 25 to form a tear strip 26 for severancefrom the can top to provide a pour opening for the liquid content. Afeature of this particular embodiment of the invention is that theleading end of the tear strip, i.e., the end where the severing actionis to be initiated, is tapered to a point.

A sheet metal tab, generally designated 28, serves as a second-classlever to initiate severance of the tear strip at the pointed leading endof the tear strip. For this purpose the tab 28 is connected to the tearstrip 26 by a hollow rivet 30 which is formed in the tear strip andextends through an aperture in the tab in overlapping engagement withthe outer surface of the tab. The tab has a fulcrum end 32 whichoverlies the tear strip 26 and has a free end with a bent up end portion34 which free end is intended to be swung upward for the leverage actionto initiate the severance of the tear strip.

It is important that the tab 28 be longitudinally rigid to serve itsbasic function as a lever and for this purpose the metal may be offsetin any suitable manner to increase the stiffness of the tab. In theconstruction shown, the tab 28 is embossed outward to form a centralstiffening rib 35 and a pair of similar outer side ribs 36, the pair ofribs straddling the rivet 30. With the two outer ribs 36 extending overthe major length of the tab and straddling the rivet 30 there is notendency for the tab to buckle adjacent the rivet when the tab functionsas a lever.

The rivet 30 lies as close as possible to the two tapered edges at theleading end of the tear strip and for this purpose the rivet iselongated longitudinally of the tear strip and is narrowed relative tothe width of the tear strip. With this arrangement, two points 38 on thescored line 25 are immediately adjacent the rivet 30 to favor initiationof severance of the tear strip at the two points. In effect, the rivetis narrowed and is nested into the angle of the tapered end of the tearstrip to place the two points 38 relatively close together andrelatively close to the leading end of the tear strip.

It is apparent that since the hollow rivet 30 is in firm overlappingengagement with the tab 28, the hollow rivet functions in effect as anintegral portion of the tab in the leverage action and since the tab isconnected to the tear strip by the hollow rivet the initial stress inthe leverage action to initiate the severance of the tear strip ismaximum at the two points 38 and therefore it is at these two pointsthat the tab tends to pull away from the hollow rivet in the leverageaction. As heretofore stated, this tendency for separation of the tabfrom the hollow rivet in the region of the two points 38 is countered bydisplacing metal of the hollow rivet towards the two opposite ends ofthe rivet as the rivet is viewed in plan.

FIGS. 4, and 6 show how the operation of expanding or heading the rivetinto engagement with the tab may be formed in a manner that creates thedesired displacement of the rivet material. In preparation for theheading operation shown in FIGS. 4, 5 and 6, the hollow rivet is formedin the sheet metal of the can top and then the hollow rivet is insertedthrough the aperture in the tab 28. To carry out the heading operation,a lower die or anvil 40 of a cross section to fit snugly into the hollowrivet is inserted into the hollow rivet into contact with the transverseend wall 42 of the hollow rivet. The two layers of metal surrounding thehollow rivet are then engaged under compression between a lower annularpressure pad 44 and an upper annular pressure pad 45. Then an upper dieor impact member 46 moves rapidly downward inside the upper pressure pad46 to cooperate with the lower die 50 to squeeze the transverse end wall42 across its thickness and thus cause the metal of the end wall to bedisplaced or extruded in all radial directions with consequent expansionof the hollow rivet in the region of the transverse end wall, theexpansion of the hollow rivet causing the rivet to make overlappingengagement with the tab 28.

To cause the metal to be displaced towards the opposite ends of therivet as the rivet is viewed in plan and at the same time to strengthenthe bead along the two opposite longitudinal sides of the rivet, theupper die 46 is formed with two downwardly extending longitudinalflanges 48 on its opposite longitudinal sides as shown in FIG. 5 tolimit the extent to which the metal may be displaced laterally in theformation of the head or bead 50 of the rivet. On the other hand, asindicated in FIG. 4 there is ample clearance space 52 at the two ends ofthe rivet when the two dies close together and consequently the metaltends to take the path of least resistance which is towards the twoopposite end clearance spaces 52. As a consequence, the bead 50 of therivet overhangs the metal of the tab to maximum extent at the twoopposite ends of the rivet and especially in the region of the twopoints 38 of the scored line that are nearest to the rivet. At the sametime, a second important result of limiting the lateral spread of themetal of the rivet is that the portions of the bead 50 on the twoopposite longitudinal sides of the rivet are thickened vertically forhigh strength in those regions.

The manner in which this first embodiment of the invention serves itspurpose is readily understood. When the free end of the tab 28 is swungupward, the fulcrum end of the tab bears downward on the tear strip 26and the hollow rivet pulls upward on the tear strip with maximumeffectiveness at the two points 38. Severance of the tear strip from themetal top begins at the two points 38 and quickly spreads first to thepointed end of the tear strip and then towards the opposite end of thetear strip.

FIG. 7 illustrating a second embodiment of the invention shows a metalcan top 60 of the same general character as the previously described cantop 20, the can top being scored in the usual manner along a continuousline 62 to form an elongated tear strip 64. A tab 28a of the characterheretofore described is attached to the tear strip 64 by means of ahollow rivet 66 that is formed in the tear strip and extends through thetab in overlapping engagement with the tab. The tab 28a has the usuallongitudinal ribs 35 and 36 and the usual bent-up free end 34.

The second embodiment of the invention differs from the first embodimentin three respects: first, in the hollow rivet 66 being round in planinstead of elongated; second, in the score line 62 being reentranttowards the rivet at a single point 68; and, third, in the tab 28a beingpositioned at an angle'to the tear strip instead of being inlongitudinal alignment with the tear strip.

The longitudinal axis of the tab 28a is indicated by the line '70 and itis to be noted that the reentrant point 68 of the scored line 62 issubstantially on this axis. It is also to be noted that the leading endof the tab 28a is tapered to provide a straight edge 72 which as viewedfrom the free end of the tab is inclined towards the right longitudinaledge of the tab and towards the free end of the tab. The edge 72 formsan acute angle with the longitudinal axis of the tab, the apex of theangle being towards the fulcrum end of the tab. The edge '72 may aptlybe termed a fulcrum edge because when the tab is lifted at its free endit tends to rock or fulcrum about the edge as an axis.

In the leverage action of the tab 28a the initial stress as well as themaximum stress is generated in the region of the reentrant point 28 tofavor in a highly effective manner initiation of severance of the tearstrip at the reentrant point, the tearing action extending in bothdirections from the reentrant point 68 along the scored line 62.

As the tab is lifted for its leverage action and rocks about the fulcrumedge 72, the fulcrum edge guides the tab in a leverage movement thatdescribes a portion of a cone, the fulcrum edge 72 being the axis of thecone. Thus the free end of the tab describes an are which is relativelylow compared to the high arc that the free end of the tab in FIG. 1describes. The relatively low are followed by the tab 28a is a path thatisnatural for the user when the users thumb and forefinger grasp thefree end of the tab and are moved arcuately by rotation of the usersWrist. It has been found that this arcuate movement is not only natural"for the user, but is also highly efiicient in that it applies maximumseverance force to the tear strip with minimum muscular effort. Afterthe leading end of the tear strip is severed by the leverage action, itis a simple matter for the user to follow through with wrist action tosevere the remainer of the tear strip from the can top.

FIG. 8 shows the state of the tear strip before the tab is lifted andFIG. 9 shows how the initial lifting of the tab causes severance of thetear strip from the can top to proceed progressively in oppositedirections from the point 68. FIG. 10 shows how the severance proceedsto a more advanced stage. When the tab is further lifted to a relativelyhigh angle, as indicated in FIG. 12, the initial severance of the tearstrip by the leverage action is completed and continued severance isaccomplished by using the tab as a handle to pull the rest of the tearstrip away from the can top.

My description in specific detail of the selected embodiments of theinvention will suggest various changes, substitutions and otherdepartures from my disclosure within the spirit and scope of theappended claims.

I claim:

1. In the structure of a container wherein a metal wall of the containeris scored along a line to form a tear strip and a hollow rivet is formedin the tear strip in overlapping engagement with a tab for use of thetab as a lever to initiate severance of the tear strip at a particularregion near one end of the tear strip, the improvement comprising:

said -rivet being elongated in plan towards the particular region andthe overhanging metal of the rivet also being displaced longitudinallytowards the particu lar region with consequent greater overhang of thebead in the portion of the joint between the tab and the tear stripwhere maximum stressing of the joint between the tear strip and the tabis created by the lever action.

2. The improvement as set forth in claim 1 in which said end of the tearstrip is tapered.

3. In the structure of a container wherein a metal wall of the containeris scored along a line to form a tear strip and a hollow rivet is formedin the tear strip in overlapping engagement with a tab for use of thetab as a lever to initiate severance of the tear, the improvementcomprising:

one end of the tear strip having two converging edges that give the endof the tear strip a tapered configuration; and

said rivet being located between and immediately adjacent to the twoconverging edges whereby two points on the converging edges,respectively, of the tear strip are points on the scored line at aminimum distance from the rivet to favor initiation of the severance ofthe tear strip at the two points.

4. The improvement set forth in claim 3 in which the rivet is elongatedtowards the tapered end of the tear strip and is thus narrowed to placetwo said points relatively close to the end of the tear strip.

5. The improvement set forth in claim 4 in which the rivet is formedwith a bead in overlapping engagement with the tab; and

in which the metal of the bead is displaced towards the tapered end ofthe tear strip to strengthen the joint between the tab and the tearstrip at the two points.

6. In a container having a sheet metal wall wherein scoring in the metalwall outlines a tear strip and wherein a tab to serve as a second-classlever to fulcrum at one end to initiate severance of the tear strip fromthe remainder .of the metal wall has a minor portion including itsfulcrum end overlapping one end of the tear strip with the minor portionattached to the tear strip and with the fulcrum end extending beyond theconnection to the tear strip, the improvement comprising:

forming the scored line with a portion offset towards the side of therivet that is furtherest removed from the fulcrum end of the tab toprovide a point on the scored line of minimum spacing from the rivet inthe region of initial stress in the lever action to cause initiation ofthe severance of the tear strip at said point.

7. The improvement set forth in claim 6 in which the longitudinal axisof the tab is at an acute angle to the tear strip and the fulcrum end ofthe tab is tapered to provide a fulcrum edge at an acute angle to thelongitudinal axis of the tab to cause the tab to rock about the fulcrumin its lever action and thereby describe a portion of a cone concentricto the fulcrum edge.

8. In a container having a sheet metal wall wherein scoring in the metalwall outlines a tear strip and wherein a tab to serve as a second-classlever to fulcrum at one end to initiate severance of the tear strip fromthe remainder of the metal wall has a minor portion includ ing itsfulcrum end overlapping one end of tear strip with the minor portionattached to the tear strip and with the fulcrum end extending beyond theconnection to the tear strip, the improvement comprising:

said one end of the tear strip being attached .to said minor portion ofthe tab by a hollow rivet formed in the tear strip and extending throughan aperture in the tab with a head of the hollow rivet in overlappingengagement with the tab,

the hollow rivet being elongated longitudinally of the tab and the metalof the bead being displaced longitudinally of the hollow rivet towardsthe free end of the tab to reinforce the engagement of the hollow rivetwith the tab on the side of the hollow rivet that is subject to maximumstress in the initial lever action of the tab.

References Cited by the Examiner UNITED STATES PATENTS 2,544,969 3/ 1951Underwood 113-421 3,070,058 12/!196-2 Boyer 113121 3,084,835 4/ 1963Walsh 22054 3,151,766 10/ 1964 Henchert 2205 4 3,191,797 6/1965 Fraze220-54 THERON E. CONDON, Primary Examiner.

G. T. HALL, Assistant Examiner.

1. IN THE STRUCTURE OF A CONTAINER WHEREIN A METAL WALL OF THE CONTAINERIS SCORED ALONG A LINE TO FORM A TEAR STRIP AND A HOLLOW RIVET IS FORMEDIN THE TEAR STRIP IN OVERLAPPING ENGAGEMENT WITH A TAB FOR USE OF THETAB AS A LEVER TO INITIATE SEVERANCE OF THE TEAR STRIP AT A PARTICULARREGION NEAR ONE END OF TEAR STRIP, THE IMPROVEMENT COMPRISING: SAIDRIVET BEING ELONGATED IN PLAN TOWARDS THE PARTICULAR REGION AND THEOVERHANGING METAL OF THE RIVET ALSO BEING DISPLACED LONGITUDINALLYTOWARDS THE PARTICU-